Deficits in quadriceps strength of the injured leg have been observed in patients following anterior cruciate ligament (ACL) reconstructions and may contribute to ACL re-injury risk. Single-leg forward hopping is a widely used task for assessing knee function in patients following ACL reconstructions as it has been shown not to be particularly challenging to the knee. This study aimed to quantify the effect of decreased quadriceps strength induced by a fatigue protocol on hopping performance and lower limb mechanics in single-leg forward, vertical, and backward hopping. Thirty-four injury-free participants performed single-leg forward, vertical, and backward hopping on both legs pre- and post-fatigue, with 1 leg experiencing a fatigue protocol. Peak moments, power, and work of hip, knee, and ankle joints were quantified during the jumping phase. Hopping performance and bilateral asymmetries in performance were assessed. Single-leg backward hopping demonstrated the greatest knee moments, power, and work compared to forward and vertical hopping, regardless of leg and fatigue. Fatigue protocol resulted in significantly less knee moments, power, and work, and decreased performance of the fatigued leg among all tasks. Bilateral symmetries in hopping performance decreased in post-fatigue, with the greatest decrease in backward hopping. The greater sensitivity of the backward hopping to detect quadriceps fatigue suggests it may act as a better or at least an additional metric to evaluate quadriceps strength deficits. The findings may contribute to the development of a clinically applicable and valid strength assessment to monitor the rehabilitation progress in patients following ACL reconstructions.

中文翻译：

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向后跳跃向前移动：与向前和垂直跳跃相比，单腿向后跳跃可以更好地检测疲劳方案引起的股四头肌力量下降


在前十字韧带 (ACL) 重建后的患者中观察到受伤腿股四头肌力量的缺陷，这可能会导致 ACL 再次受伤的风险。单腿向前跳跃是一项广泛使用的任务，用于评估 ACL 重建后患者的膝关节功能，因为它已被证明对膝关节来说并不是特别具有挑战性。本研究旨在量化疲劳方案引起的股四头肌力量下降对单腿向前、垂直和向后跳跃的跳跃性能和下肢力学的影响。 34 名未受伤的参与者在疲劳前和疲劳后进行了单腿向前、垂直和向后跳跃，其中一条腿经历了疲劳方案。在跳跃阶段对髋关节、膝关节和踝关节的峰值力矩、功率和工作进行了量化。评估了跳跃性能和双边性能不对称性。与向前和垂直跳跃相比，单腿向后跳跃表现出最大的膝力矩、力量和工作量，无论腿部和疲劳程度如何。疲劳方案会导致膝关节力矩、力量和工作量显着减少，并且疲劳腿在所有任务中的表现都会下降。疲劳后跳跃性能的双边对称性下降，其中向后跳跃下降幅度最大。向后跳跃检测股四头肌疲劳的灵敏度更高，这表明它可以作为评估股四头肌力量缺陷的更好或至少是附加指标。这些发现可能有助于开发临床适用且有效的力量评估，以监测 ACL 重建后患者的康复进展。